SURFACE AND UNDERGROUND DRAINS - Part 2

Articles In This Section:

· WATER, AIR, AND BACTERIA

· SOILS THAT NEED DRAINAGE

· DRAIN OUTLETS

· SURFACE AND UNDERGROUND DRAINS - Part 1

· SURFACE AND UNDERGROUND DRAINS - Part 2

The drainage scheme will function better if the pipes are covered with cinders, coarse gravel, or brushwood, which will filter silt out of water making its way to the pipes. It is advisable to lay four-inch strips of heavy bagging over the joins.

Fig. 6. Two alternate schemes for drainage. The choice will depend on the area to be drained and the contour of the land. Many prefer to bring the side drains to joints in the main drain.

Although the bagging rots in time, it serves its purpose until the disturbed soil has settled and, after that, silt is unlikely to enter the pipes. Water reaches the pipes through the small spaces between them, and to a small extent through their pores. Pipe-lines should be no more than twelve feet apart. They can be laid fish-tail fashion, emptying into a larger main drain. Usually the smaller pipes are two inches in diameter and the larger three inches; but three-inch pipes may be used through-out and are probably better. Where the ground has a steep slope it is best to run the drains across the slope where they will catch much more soakage. If they run down the slope they are inclined to scour and move.

Keep large trees away from drain-pipes. Poplars, wattles, cypress, and citrus are the worst types of tree.

Efficient drainage is far more important than watering or manuring, and every gardener knows that it is the first prerequisite of success, and that no garden or soil will be harmed by the installation of a drainage system.

Well-drained soil is almost always acid and has a rather coarse crumb-structure, which helps in the process of aeration. Poorly drained soil is almost always alkaline and has a fine crumb-structure, making it inadequately permeable.

In roses, the outstanding symptoms of poor soil drainage are a form of die-back, undersized foliage of pale colour, poor growth, and numerous blind shoots-branches that do not produce a terminal flower. Also, the flowers have a lack of brilliance, a marked tendency for the reds to be purplish (they are said to "blue") and the pinks to be mauve, as well as there being a great number of badly formed blooms with petals deficient in number, size, and texture, and with short, weak stems. The die-back affects both old and young wood. In the young growth the new shoot often grows to a length of four to ten inches and then, for no apparent reason, withers at the tip and fairly quickly dies back to its base without having formed even a small flower-bud, in much the same way as a rose behaves when affected by rose wilt. Poor drainage seems to be the commonest cause of blind shoots.